The idler pulley is wet on the edges where the serpintine belt doesn't ride.
The bolts that hold the flange that the idler pulley is mounted to are also wet.
The ground below is wet too.
Any ideas on where the leak is originating from?

On my 03' it was from the engine oil cooler. It's mounted in the water jacket behind the oil filter.it would run down the edge of the front cover and sometimes drip off of the ac pump. It was a slow leak for about a year (one drip per night ) untill I found it.